On Thu, 2017-11-09 at 07:49 -0700, Jan Beulich wrote: > See the code comment being added for why we need this. > > Reported-by: Igor Druzhinin <igor.druzhi...@citrix.com> > Signed-off-by: Jan Beulich <jbeul...@suse.com> > > --- a/xen/arch/x86/hvm/vmx/vmx.c > +++ b/xen/arch/x86/hvm/vmx/vmx.c > @@ -479,7 +479,13 @@ static void vmx_vcpu_destroy(struct vcpu > * we should disable PML manually here. Note that vmx_vcpu_destroy is > called > * prior to vmx_domain_destroy so we need to disable PML for each vcpu > * separately here. > + * > + * Before doing that though, flush all state for the vCPU previously > having > + * run on the current CPU, so that this flushing of state won't happen > from > + * the TLB flush IPI handler behind the back of a vmx_vmcs_enter() / > + * vmx_vmcs_exit() section. > */ > + sync_local_execstate(); > vmx_vcpu_disable_pml(v); > vmx_destroy_vmcs(v); > passive_domain_destroy(v);
This patch fixes only one particular issue and not the general problem. What if vmcs is cleared, possibly in some future code, at another place? The original intent of vmx_vmcs_reload() is correct: it lazily loads the vmcs when it's needed. It's just the logic which checks for v->is_running inside vmx_ctxt_switch_from() is flawed: v might be "running" on another pCPU. IMHO there are 2 possible solutions: 1. Add additional pCPU check into vmx_ctxt_switch_from() 2. Drop v->is_running check inside vmx_ctxt_switch_from() making vmx_vmcs_reload() unconditional. Thanks, Sergey _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
